This invention relates to heat resistant nickel base alloys, and more particularly to heat resistant nickel base alloys of the solid solution strengthening type which are excellent in hot workability and cold workability as well as tensile strength and fatigue strength at high temperatures and also possess satisfactory oxidation resistance.
Conventionally, heat resistant nickel base alloys such as Hastelloy X have fairly long been used as component parts of various high-temperature apparatuses for prime movers including gas turbine combustors, and also as component parts of various high-temperature apparatuses for use in the chemical industry and the nuclear energy industry, etc. In recent years there have been desired new materials which can withstand use as component parts of the above various high-temperature apparatuses under severer conditions. In order to meet such demand, various heat resistant alloys have been developed and actually used under the name of superalloys. On the other hand, nowadays the aforementioned high-temperature apparatuses trend toward higher efficiency. To respond to this trend, more rigorous requirements are generally imposed upon materials for these high-temperature apparatuses in respect of oxidation resistance, high temperature strength, high temperature flexural fatigue strength, hot workability, cold workability, etc. However, it is a general tendency in designing such alloys that the improvements in the high temperature strength and the high temperature flexural fatique strength are incompatible with those in the hot workability and the cold workability. For instance, excellent hot workability and cold workability are given by Ni-Cr-Mo-Fe alloys represented by Hastelloy X, and Ni-Cr-Mo-Co alloys, which are heat resistant nickel base alloys of the solid solution strengthening type and conventionally used as nickel base super alloys. Therefore, these conventional alloys can be satisfactorily wrought. However, these alloys generally do not fully satisfy recent higher requirements in respect of high temperature characteristics such as high temperature strength and high temperature flexural fatigue strength.